Robin Williams was not only a great actor and comedian, but he was also, apparently, a great alarm clock. In 1988, the five astronauts aboard the space shuttle Discovery received a peculiar and unexpected wake-up call from none other than Robin Williams. Playing upon his previous role as radio DJ from the year before in 1987 film Good Morning, Vietnam, Williams provided the astronauts with some of his typical humor and comedy on their second day in flight.

Because orbiting the planet takes just 90 minutes, the astronauts experienced numerous sunrises and sunsets within a 24-hour period. So NASA began making wake-up calls, mostly using songs, to help ease the astronaut’s disrupted sleep cycles. Williams’ 1988 wake-up call was particularly significant because that shuttle was the first mission to return to flight after the Challenger disaster and tragedy in 1986.

Williams’ wake-up call is one of his many memorable contributions to the world and one of many ways we remember and celebrate the beloved actor and comedian since his tragic death on Monday.